A controversial law effectively banning parents from smacking their children has been passed by New Zealand's parliament.

The legislation closes a legal loophole that allowed parents to use "reasonable force" to discipline their child.

However, the new bill allows the police to use discretion over whether a parent should be prosecuted or not.

Supporters say the previous law was too lenient, but critics say the new rules intrude too far into family life.

The bill was passed overwhelmingly, with only seven MPs voting against it.

It amends the New Zealand's Crimes Act, to remove the provision of "reasonable force" for parents in the disciplining of their children.

Critics of the old law said such a provision had helped acquit parents in child abuse cases.

But the changes - first proposed in 2005 - stirred huge concern from conservative groups worried that it would make criminals of parents.

To allay fears, a clause was added giving police the power "not to prosecute complaints.. where the offence is considered so inconsequential there is no public interest in proceeding with a prosecution."

Poor record

The bill's sponsor, Green Party MP Sue Bradford, said the aim of the new law is to stop child-beaters from using "reasonable force" as a legal defence - and not to prevent a parent from smacking a child.

New Zealand has on its conscience that our rate of child death and injury from violence, including in the home, is appalling